As spying on web users turns into big business, the Wall Street Journal takes a look at the booming industry and says the "tracking of consumers has grown both far more pervasive and far more intrusive than is realized by all but a handful of people in the vanguard of the industry." The paper examined the 50 most popular websites in the United States to measure just how many tracking devices are installed on each visitor's computer. While the fact that sites install cookies on computers is hardly news, the sheer number of them currently in use is revealing. The 50 sites installed a total of 3,180 "tracking files" on the WSJ's test computer, an average of 64 pieces of tracking technology per site. A dozen sites installed more than 100. Wikipedia was the only site in the top 50 that didn't install anything on a visitor's computer, while Dictionary.com was the worst offender with "234 files or programs being downloaded on the Journal's test computer." These tracking devices once only kept track of the websites users visited, but now the information is much broader and includes so much personally identifying information that it puts into question assurances that the tracking is done anonymously. Companies then create profiles of users that are traded "on stock-market-like exchanges that have sprung up in the past 18 months," reports the WSJ. Some insist the industry is crying out for regulation because there is so much consumer data available and few legal limits on how it can be used by companies eager to make some cash.